This invention relates generally to inboard motor-driven vessels, and more particularly to a rudderless motorboat propelled and steered by twin turbine-wheels also functioning as traction wheels to carry the boat over sandbars and other submerged bodies to prevent it from running aground.
The typical motorboat is propelled by means of screw propellers driven by inboard or outboard motors. In an outboard motor installation, the engine is usually supported on the stern board of the hull with a resultant poor weight distribution, particularly in the case of a large horsepower motor. In an inboard motor arrangement, the screw-propeller is mounted at the end of an inclined shaft which extends into the boat through the keel or bottom ribs of the hull at a slight angle thereto, usually about 15.degree.. Consequently, the inboard engine coupled to the shaft must be mounted within the hull at an inclined position.
An inboard motor has the advantage of providing a better weight distribution than an outboard motor installation. On the other hand, because the drive shaft in an inboard motor passes through an opening which pierces the keel or bottom ribs of the hull, this somewhat weakens the hull structure. Also, in an inboard motor arrangement, the engine power is not fully utilized in propelling the boat, since the screw propeller is at an angle relative to the water line.
Moreover, in a conventional inboard motor installation, since the front of the engine is somewhat higher than the rear thereof, oil starvation is often experienced which may be damaging to the engine. With an inclined engine mounting, float problems and erratic fuel supply encountered at high speeds or in choppy waters give rise to rusty pump and jet parts and eventually to engine breakdown.
But the more serious drawback of existing inboard and outboard motor boats which make use of screw propellers, rudders, shafts and other mechanical elements which project into the water below the bottom of the hull, is that these elements are exposed and subject to mutilation and crippling by floating debris or other water-borne bodies. Furthermore, in shallow water, should the boat run over a sandbar or a submerged rock, the elements projecting below the boat may be seriously damaged thereby and the boat run aground. Most boating accidents are imputable to the vulnerability of the mechanical elements of the board which project below the bottom of the hull.
Thus the inherent nature of existing types of motor-driven boats is such as to render these boats accident prone and inefficient in terms of power utilization.